Search

Background: The SARS-COV-2 (Covid-19) pandemic has impacted the management of patients with hematologic disorders. In some entities, an increased risk for Covid-19 infections was reported, whereas others including chronic myeloid leukemia (CML) had a lower mortality. We have analyzed the prevalence of Covid-19 infections in patients with mastocytosis during the Covid-19 pandemic in comparison to data from CML patients and the general Austrian population., Materials and Methods: The prevalence of infections and PCR-proven Covid-19 infections was analyzed in 92 patients with mastocytosis. As controls, we used 113 patients with CML and the expected prevalence of Covid-19 in the general Austrian population., Results: In 25% of the patients with mastocytosis (23/92) signs and symptoms of infection, including fever (n = 11), dry cough (n = 10), sore throat (n = 12), pneumonia (n = 1), and dyspnea (n = 3) were recorded. Two (8.7%) of these symptomatic patients had a PCR-proven Covid-19 infection. Thus, the prevalence of Covid-19 infections in mastocytosis was 2.2%. The number of comorbidities, subtype of mastocytosis, regular exercise, smoking habits, age, or duration of disease at the time of interview did not differ significantly between patients with and without Covid-19 infections. In the CML cohort, 23.9% (27/113) of patients reported signs and symptoms of infection (fever, n = 8; dry cough, n = 17; sore throat, n = 11; dyspnea, n = 5). Six (22.2%) of the symptomatic patients had a PCR-proven Covid-19 infection. The prevalence of Covid-19 in all CML patients was 5.3%. The observed number of Covid-19 infections neither in mastocytosis nor in CML patients differed significantly from the expected number of Covid-19 infections in the Austrian population., Conclusions: Our data show no significant difference in the prevalence of Covid-19 infections among patients with mastocytosis, CML, and the general Austrian population and thus, in mastocytosis, the risk of a Covid-19 infection was not increased compared to the general population., (© 2022 The Authors. European Journal of Haematology published by John Wiley & Sons Ltd.)

Personalized medicine aims to match the right drug with the right patient by using specific features of the individual patient's tumor. However, current strategies of personalized therapy matching provide treatment opportunities for less than 10% of patients with cancer. A promising method may be drug profiling of patient biopsy specimens with single-cell resolution to directly quantify drug effects. We prospectively tested an image-based single-cell functional precision medicine (scFPM) approach to guide treatments in 143 patients with advanced aggressive hematologic cancers. Fifty-six patients (39%) were treated according to scFPM results. At a median follow-up of 23.9 months, 30 patients (54%) demonstrated a clinical benefit of more than 1.3-fold enhanced progression-free survival compared with their previous therapy. Twelve patients (40% of responders) experienced exceptional responses lasting three times longer than expected for their respective disease. We conclude that therapy matching by scFPM is clinically feasible and effective in advanced aggressive hematologic cancers. SIGNIFICANCE: This is the first precision medicine trial using a functional assay to instruct n-of-one therapies in oncology. It illustrates that for patients lacking standard therapies, high-content assay-based scFPM can have a significant value in clinical therapy guidance based on functional dependencies of each patient's cancer. See related commentary by Letai, p. 290 . This article is highlighted in the In This Issue feature, p. 275 ., (©2021 The Authors; Published by the American Association for Cancer Research.)

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disease characterized by a deregulated complement system, chronic Coombs-negative, intravascular hemolysis, and a variable clinical course with substantial risk to develop thromboembolic events. We analyzed diagnostic and prognostic parameters as well as clinical endpoints in 59 adult patients suffering from PNH in 5 hematology centers in Austria (observation period: 1978-2015). Median follow-up time was 5.6 years. The median clone size at diagnosis amounted to 55% and was higher in patients with classical PNH (81%) compared to patients with PNH associated with aplastic anemia (AA) or myelodysplastic syndromes (MDS) (50%). The clone size also correlated with lactate dehydrogenase (LDH) levels. In one patient, anemia improved spontaneously and disappeared with complete normalization of LDH after 16 years. Seventeen patients received therapy with eculizumab. The rate of thromboembolic events was higher in the pre-eculizumab era compared with eculizumab-treated patients but did not correlate with the presence of age-related clonal hematopoiesis or any other clinical or laboratory parameters. Peripheral blood colony-forming progenitor cell counts were lower in PNH patients compared with healthy controls. Only two patients with classical PNH developed MDS. Overall, 7/59 patients died after 0.5-32 years. Causes of death were acute pulmonary hypertension, Budd-Chiari syndrome, and septicemia. Overall survival (OS) was mainly influenced by age and was similar to OS measured in an age-matched healthy Austrian control cohort. Together, compared with previous times, the clinical course and OS in PNH are favorable, which may be due to better diagnosis, early recognition, and eculizumab therapy.

Background: Several clinical trials in chronic phase (CP) chronic myeloid leukemia (CML) showed that early response to tyrosine kinase inhibitor (TKI) treatment results in an improved long-term survival and progression-free survival. This study assessed whether patients achieving early treatment response (ETR; partial cytogenetic response or BCR-ABL1 mRNA ≤10% at 3 months) in daily practice also have a long-term survival benefit., Methods: The Retrospective Evaluation of Early response in CML for long-term Treatment outcome (R-EFECT), a multicenter, retrospective chart review, documented patients with newly diagnosed CML-CP starting first-line TKI therapy in routine clinical practice. The primary aim was to assess the 5‑year overall survival rate., Results: Of the 211 patients from 12 centers across Austria (January 2004-May 2010), 176 (median age, 56 years) were included in the analysis. All patients received first-line therapy with imatinib. Overall, 136 patients (77.3%) achieved ETR (ETR+ group), whereas 40 (22.7%) did not reach ETR (ETR- group). The ETR+ group had higher 5‑year overall survival (92.5% vs. 77.5%, P = 0.018) and progression-free survival (95.6% vs. 87.5%, P = 0.06) rates compared with the ETR- group. As expected, more patients in the ETR- group were switched to another TKI. At the last contact, 120 patients were still on imatinib and 44 had switched to another TKI (25 to nilotinib, 15 to dasatinib, and 4 to bosutinib)., Conclusion: The data are in line with randomized trials demonstrating that ETR is associated with improved survival and thus confirmed these results in patients treated in daily clinical routine.

In the Austrian biodatabase for chronic myelomonocytic leukemia (ABCMML) clinicolaboratory real-life data have been captured from 606 CMML patients from 14 different hospitals over the last 30 years. It is the only large biodatabase worldwide in which functional methods such as semisolid in vitro cultures complement modern molecular methods such as next generation sequencing. This provides the possibility to comprehensively study the biology of CMML. The aim of this study was to compare patient characteristics with published CMML cohorts and to validate established prognostic parameters in order to examine if this real-life database can serve as a representative and useful data source for further research. After exclusion of patients in transformation characteristics of 531 patients were compared with published CMML cohorts. Median values for age, leukocytes, hemoglobin, platelets, lactate dehydrogenase (LDH) and circulating blasts were within the ranges of reported CMML series. Established prognostic parameters including leukocytes, hemoglobin, blasts and adverse cytogenetics were able to discriminate patients with different outcome. Myeloproliferative (MP) as compared to myelodysplastic (MD)-CMML patients had higher values for circulating blasts, LDH, RAS-pathway mutations and for spontaneous myelomonocytic colony growth in vitro as well as more often splenomegaly. This study demonstrates that the patient cohort of the ABCMML shares clinicolaboratory characteristics with reported CMML cohorts from other countries and confirms phenotypic and genotypic differences between MP-CMML and MD-CMML. Therefore, results obtained from molecular and biological analyses using material from the national cohort will also be applicable to other CMML series and thus may have a more general significance.

Background: The majority of patients with periodontitis present with comorbidities, however only little is known on prevalence of these comorbidities in comparison with the general population. This study aims to analyze the prevalence and impact of comorbidities in patients with periodontitis in Austria., Methods: Prevalence of comorbidities was evaluated in 1,199 patients with periodontitis (median age: 49, range: 14 to 83 years). These data were compared with a randomly selected age- and sex-matched cohort of the Austrian population by an unconditional logistic regression model., Results: Comorbidities were found in 821 of 1,199 (68.5%) patients. Allergies had the highest prevalence (29.2%), followed by hypertension (19.4%), musculoskeletal (11.2%), and endocrine disorders (9.7%). Chronic pulmonary disorders (no influenza/pneumonia) were associated with a higher approximal plaque index (72% versus 63%, P = 0.02). No association between characteristics of periodontitis and comorbidities was observed. Prevalence of allergies (29.2% versus 22.9%) and pulmonary disorders (8.5% versus 4.3%) was significantly higher in periodontitis patients compared with the Austrian population (P < 0.001), whereas asthma (1.5% versus 5.6%), cardiovascular disorders (1.8% versus 10.5%), depression (7.1% versus 10.4%), headache (1.3% versus 20%), hyperlipidemia (6.4% versus 14.8%), hypertension (14.2% versus 24.5%), musculoskeletal disorders (11.2% versus 41.7%), and osteoporosis (2.8% versus 5.1%) were found less frequently (P < 0.001). No differences were observed for cancer, diabetes mellitus, gastrointestinal disorders, or psychiatric disorders (P = 0.95, P = 0.76, P = 0.68, P = 0.23, respectively)., Conclusion: In Austria, the majority of patients with periodontitis present with comorbidities, and the adjusted prevalence differs significantly from the general population., (© 2017 American Academy of Periodontology.)

Background: The MDS-IWG and NCCN currently endorse both FAB and WHO classifications of MDS and AML, thus allowing patients with 20-30 % bone marrow blasts (AML20-30, formerly MDS-RAEB-t) to be categorised and treated as either MDS or AML. In addition, an artificial distinction between AML20-30 and AML30+ was made by regulatory agencies by initially restricting approval of azacitidine to AML20-30. Thus, uncertainty prevails regarding the diagnosis, prognosis and optimal treatment timing and strategy for patients with AML20-30. Here, we aim to provide clarification for patients treated with azacitidine front-line., Methods: The Austrian Azacitidine Registry is a multicentre database (ClinicalTrials.gov: NCT01595295). For this analysis, we selected 339 patients treated with azacitidine front-line. According to the WHO classification 53, 96 and 190 patients had MDS-RAEB-I, MDS-RAEB-II and AML (AML20-30: n = 79; AML30+: n = 111), respectively. According to the FAB classification, 131, 101 and 111 patients had MDS-RAEB, MDS-RAEB-t and AML, respectively., Results: The median ages of patients with MDS and AML were 72 (range 37-87) and 77 (range 23-93) years, respectively. Overall, 80 % of classifiable patients (≤30 % bone marrow blasts) had intermediate-2 or high-risk IPSS scores. Most other baseline, treatment and response characteristics were similar between patients diagnosed with MDS or AML. WHO-classified patients with AML20-30 had significantly worse OS than patients with MDS-RAEB-II (13.1 vs 18.9 months; p = 0.010), but similar OS to patients with AML30+ (10.9 vs 13.1 months; p = 0.238). AML patients that showed MDS-related features did not have worse outcomes compared with patients who did not (13.2 vs 8.9 months; p = 0.104). FAB-classified patients with MDS-RAEB-t had similar survival to patients with AML30+ (12.8 vs 10.9 months; p = 0.376), but significantly worse OS than patients with MDS-RAEB (10.9 vs 24.4 months; p < 0.001)., Conclusions: Our data demonstrate the validity of the WHO classification of MDS and AML, and its superiority over the former FAB classification, for patients treated with azacitidine front-line. Neither bone marrow blast count nor presence of MDS-related features had an adverse prognostic impact on survival. Patients with AML20-30 should therefore be regarded as having 'true AML' and in our opinion treatment should be initiated without delay.

Purpose: Pump-driven veno-venous extracorporeal CO2-removal (ECCO2-R) increasingly takes root in hypercapnic lung failure to minimize ventilation invasiveness or to avoid intubation. A recently developed device (iLA activve(®), Novalung, Germany) allows effective decarboxylation via a 22 French double lumen cannula. To assess determinants of gas exchange, we prospectively evaluated the performance of ECCO2-R in ten patients receiving iLA activve(®) due to hypercapnic respiratory failure., Methods: Sweep gas flow was increased in steps from 1 to 14 L/min at constant blood flow (phase 1). Similarly, blood flow was gradually increased at constant sweep gas flow (phase 2). At each step gas transfer via the membrane as well as arterial blood gas samples were analyzed., Results: During phase 1, we observed a significant increase in CO2 transfer together with a decrease in PaCO2 levels from a median of 66 mmHg (range 46-85) to 49 (31-65) mmHg from 1 to 14 L/min sweep gas flow (p < 0.0001), while arterial oxygenation deteriorated with high sweep gas flow rates. During phase 2, oxygen transfer significantly increased leading to an increase in PaO2 from 67 (49-87) at 0.5 L/min to 117 (66-305) mmHg at 2.0 L/min (p < 0.0001). Higher blood flows also significantly enhanced decarboxylation (p < 0.0001)., Conclusions: Increasing sweep gas flow results in effective CO2-removal, which can be further reinforced by raising blood flow. The clinically relevant oxygenation effect in this setting could broaden the range of indications of the system and help to set up an individually tailored configuration.

Background: Patients with malignancies are at increased risk of serious influenza related complications with higher rates of hospitalization and mortality than healthy cohorts. Although annual vaccination against influenza infection is recommended, vaccination rates among cancer patients are apparently low. The reasons for the low compliance to influenza vaccine and the influenza vaccination rate among Austrian cancer patients have not been studied in detail yet., Patients and Methods: From July 1, 2013 to October 31, 2013, 444 patients treated in the outpatient departments of the Clinical Division of Oncology and the Clinical Division of Haematology and Haemostaseology of the General Hospital Vienna participated in a survey on different aspects of influenza vaccination., Results: In total, only 80 out of 444 patients (18%) had received influenza vaccination in the previous year. The influenza vaccination rate was higher amongst patients with haematological malignancies (22%) compared to patients with solid tumours (13%). Higher age was significantly associated with a higher probability for being vaccinated. Collecting information about influenza vaccination primarily from media or the internet was not significantly associated with influenza vaccination status. Information through a medical consultation or a recommendation by the attending physician resulted in significant higher influenza vaccination coverage rates. Only 199 out of the 444 patients (44.8%) were informed by a physician about influenza vaccination and only 18 out of 337 patients (5.3%) with a diagnosis of a malignant disease were informed by their treating oncologist. The main reasons for influenza vaccination denial were concerns about interaction with the malignant disease and potential side-effects., Conclusion: Information about influenza vaccination during a medical consultation and a clear recommendation by the attending physician are highly predictive for acceptance of influenza vaccination. Increased awareness among physicians, especially oncologists is of utmost importance to effectively improve IVR in patients with malignant disease., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The Austrian myelodysplastic syndromes (MDS) Platform was founded as a national working group in 2003 to initiate and coordinate common projects in the field. The incidence of MDS in Austria is approximately 400-500 new MDS cases per year. The overall low number of MDS patients underlines the importance of a national initiative to concentrate knowledge at certain specialized centres, where treatment of these patients mainly takes place. Clinical trials as well as basic research are facilitated by the cooperation of university and non-university hospitals. Other objectives are the generation of therapeutic standards, organization of meetings to spread this information to physicians and patients as well as promoting patient-support groups. Cooperation with international working groups is another important aim of the Platform. The 10th anniversary of the Austrian MDS Platform was organized as a meeting for all interested physicians throughout Austria providing an update on the disease and ongoing projects.

Data on efficacy and safety of azacitidine in acute myeloid leukemia (AML) with >30 % bone marrow (BM) blasts are limited, and the drug can only be used off-label in these patients. We previously reported on the efficacy and safety of azacitidine in 155 AML patients treated within the Austrian Azacitidine Registry (clinicaltrials.gov identifier NCT01595295). We herein update this report with a population almost twice as large (n = 302). This cohort included 172 patients with >30 % BM blasts; 93 % would have been excluded from the pivotal AZA-001 trial (which led to European Medicines Agency (EMA) approval of azacitidine for high-risk myelodysplastic syndromes (MDS) and AML with 20-30 % BM blasts). Despite this much more unfavorable profile, results are encouraging: overall response rate was 48 % in the total cohort and 72 % in patients evaluable according to MDS-IWG-2006 response criteria, respectively. Median OS was 9.6 (95 % CI 8.53-10.7) months. A clinically relevant OS benefit was observed with any form of disease stabilization (marrow stable disease (8.1 months), hematologic improvement (HI) (9.7 months), or the combination thereof (18.9 months)), as compared to patients without response and/or without disease stabilization (3.2 months). Age, white blood cell count, and BM blast count at start of therapy did not influence OS. The baseline factors LDH >225 U/l, ECOG ≥2, comorbidities ≥3, monosomal karyotype, and prior disease-modifying drugs, as well as the response-related factors hematologic improvement and further deepening of response after first response, were significant independent predictors of OS in multivariate analysis. Azacitidine seems effective in WHO-AML, including patients with >30 % BM blasts (currently off-label use). Although currently not regarded as standard form of response assessment in AML, disease stabilization and/or HI should be considered sufficient response to continue treatment with azacitidine.

Objectives: Myelodysplastic syndromes (MDS) are typical diseases of the elderly. The clinical outcome of a well-characterized cohort of patients with MDS was analyzed for prevalence and impact of comorbidities to establish the basis for tailored treatment algorithms. Focus was on age- and sex-related differences., Material and Methods: The hematopoietic cell transplantation-comorbidity index (HCT-CI) was assessed in 616 well-defined patients from the Austrian MDS platform (median age: 71years)., Results: Most patients displayed one (24.5%) or more (23.7%) comorbidities. The highest frequencies were observed for cardiovascular disease (28.4%), diabetes (12.2%), and prior tumors (9.9%). Comorbidities were more frequent (mean number: 0.92 vs. 0.74 [male vs. female]; p=0.030) and more severe in men than in women (mean HCT-CI score: 1.41 vs. 1.09 [male vs. female]; p=0.016). Elderly patients (65+years) showed a higher prevalence of comorbidities than younger patients (HCT-CI score: 1.52, mean in 65+, vs. 0.24 and 0.76 in <45years and 46-65years, respectively) (p<0.001). These differences were most pronounced for cardiovascular disease, diabetes, and prior tumors (p<0.001). Presence of cardiac arrhythmia or prior solid tumor was significantly associated with shorter overall survival (p=0.023, 0.024, respectively). Moreover, HCT-CI risk grouping remained an independent prognostic parameter for survival in multivariate analysis., Conclusions: Comorbidities impact clinical outcome in elderly patients with MDS. Distinct diseases cluster in an age- and sex-related manner, which may have clinical implications when designing individualized therapies. Comorbidities should be evaluated with established scores and integrated in decision making., (Copyright © 2014. Published by Elsevier Ltd.)

Background: Patient selection for various therapies in myelodysplastic syndromes (MDS) is based on prognostic factors, scoring systems and the individual life expectancy. However, most established risk scores include mainly disease-related parameters and thus focus on leukaemia-transformation rather than survival., Patients and Methods: To establish a risk score optimized for prediction of survival, we analysed international prognostic scoring system (IPSS)-related and IPSS-independent variables in 400 patients with primary MDS (median age: 71 years; range 18-91) of the Austrian MDS platform. Patients were randomly split into a learning sample (60%) and validation sample (40%). External validation was performed on 93 patients from the Heinrich Heine University (Duesseldorf/Germany)., Results: By multivariate analysis, IPSS, ferritin, age and comorbidities were found to be independent predictive variables concerning survival. Based on weighing these prognostic parameters against each other, we established a novel survival score employing IPSS, ferritin (< 900 ng/mL = 0; ≥ 900 ng/mL = 1), age (< 70 years = 0; 70-79 years = 1; ≥ 80 years = 1.5) and HCT-CI comorbidity (low/intermediate = 0; high = 0.5). Using this score, four prognostic risk groups could be discriminated in the validation sample, with highly significant differences in life expectancy [median survival: LowS (score 0), not reached; Int-1S (score 0.5-1.0), 3.84 years; Int-2S (score 1.5-2.0): 2.72 years; and HighS (score > 2.0): 0.80 years; P < 0.0001]., Conclusions: Our newly proposed score may be a useful tool for survival prediction in MDS and helpful in patient selection for various therapies in daily practice and clinical trials., (© 2013 Stichting European Society for Clinical Investigation Journal Foundation. Published by John Wiley & Sons Ltd.)

We report on 17 patients with influenza A H1N1v-associated Adult Respiratory Distress Syndrome who were admitted to the intensive care unit (ICU) between June 11th 2009 and August 10th 2010 (f/m: 8/9; age: median 39 (IQR 29-54) years; SAPS II: 35 (29-48)). Body mass index was 26 (24-35), 24% were overweight and 29% obese. The Charlson Comorbidity Index was 1 (0-2) and all but one patient had comorbid conditions. The median time between onset of the first symptom and admission to the ICU was 5 days (range 0-14). None of the patients had received vaccination against H1N1v. Nine patients received oseltamivir, only two of them within 48 hours of symptom onset. All patients developed severe ARDS (PaO(2)/FiO(2)-Ratio 60 (55-92); lung injury score 3.8 (3.3-4.0)), were mechanically ventilated and on vasopressor support. Fourteen patients received corticosteroids, 7 patients underwent hemofiltration, and 10 patients needed extracorporeal membrane-oxygenation (ECMO; 8 patients veno-venous, 2 patients veno-arterial), three patients Interventional Lung Assist (ILA) and two patients pump driven extracorporeal low-flow CO(2)-elimination (ECCO(2)-R). Seven of 17 patients (41%) died in the ICU (4 patients due to bleeding, 3 patients due to multi-organ failure), while all other patients survived the hospital (59%). ECMO mortality was 50%. The median ICU length-of-stay was 26 (19-44) vs. 21 (17-25) days (survivors vs. nonsurvivors), days on the ventilator were 18 (14-35) vs. 20 (17-24), and ECMO duration was 10 (8-25) vs. 13 (11-16) days, respectively (all p = n.s.). Compared to a control group of 241 adult intensive care unit patients without H1N1v, length of stay in the ICU, rate of mechanical ventilation, days on the ventilator, and TISS 28 scores were significantly higher in patients with H1N1v. The ICU survival tended to be higher in control patients (79 vs. 59%; p = 0.06). Patients with H1N1v admitted to either of our ICUs were young, overproportionally obese and almost all with existing comorbidities. All patients developed severe ARDS, which could only be treated with extracorporeal gas exchange in an unexpectedly high proportion. Patients with H1N1v had more complicated courses compared to control patients.

Background: The evaluation of comorbidity is of increasing importance in patients with hematologic disorders., Patients and Methods: In the present study, the influence of comorbidity on survival and acute myeloid leukemia (AML) evolution was analyzed retrospectively in 419 patients with de novo myelodysplastic syndromes (MDS) (observation period: 1985-2007). The median age was 71 years (range 24-91 years). Two different scoring systems, the hematopoietic stem-cell transplantation-specific comorbidity index (HCT-CI) and the Charlson comorbidity index (CCI) were applied., Results: The HCT-CI was found to be a significant prognostic factor for overall survival (OS, P < 0.05) as well as event-free survival (EFS, P < 0.05) in our patients, whereas the CCI was of prognostic significance for OS (P < 0.05), but not for EFS. For AML-free survival, neither the HCT-CI nor the CCI were of predictive value. A multivariate analysis including age, lactate dehydrogenase, ferritin, karyotype, number of cytopenias, French-American-British groups, and comorbidity was applied. Comorbidity was found to be an independent prognostic factor in patients with low- or int-1-risk MDS (P < 0.05) regarding OS and EFS., Conclusions: Together, our data show that comorbidity is an important risk factor for OS and EFS in patients with MDS.

Background: Recent data suggest that, among other factors, comorbidity may be an important prognostic variable in patients with myelodysplastic syndromes (MDS) who are eligible for haematopoietic stem cell transplantation (SCT)., Patients and Methods: We examined the overall survival (OS) and underlying risk factors in 45 adult patients with MDS (n = 38), chronic myelomonocytic leukaemia (n = 1), or secondary acute myeloid leukaemia (AML) arising from MDS (n = 6), who underwent allogeneic SCT at our Institution., Results: With a median follow-up of 37 months, OS for all patients was 23%, post-transplant relapse occurred in 11 patients, and 10 patients died from treatment-related complications. The overall outcome and survival was independent of cytogenetic abnormalities and International Prognostic Scoring System (IPSS). However, we identified comorbidity as defined by the haematopoietic cell transplantation specific comorbidity index (HCT-CI), as a significant adverse prognostic variable in our MDS patients., Conclusions: Based on these data and similar published data we recommend selecting patients with MDS or secondary AML for SCT according to the presence of comorbidities.

Background: In contrast to aggressive mastocytosis, patients with indolent systemic mastocytosis (ISM) usually present with urticaria pigmentosa-like skin lesions. In those who lack skin lesions, mastocytosis is often overlooked or confused with endocrinologic, allergic, or other internal disorders., Case Report and Results: We report on a 33-year-old male patient in whom severe hypotensive episodes occurred after contact with ants or yellow jackets. Since no specific IgE was detected, the serum tryptase concentration was measured and found to be clearly elevated (70 ng/ml). Consecutive staging and examination of the bone marrow revealed ISM. The patient was advised to circumvent insect contact, to take antihistamines on demand, and to carry an epinephrine self-injector for emergency events. In a retrospective analysis of 40 patients seen between 1988 and 2003, only 2 had a life-threatening mediator-related episode before ISM was diagnosed., Conclusions: Our report confirms the diagnostic value of tryptase in patients with suspected mastocytosis. In addition, the report suggests that the lack of typical skin lesions does not exclude an indolent form of mastocytosis even if the serum tryptase is clearly elevated. Finally, our case further shows that mastocytosis can be an important differential diagnosis to be considered in patients with unexplained anaphylactoid or other mediator-related symptoms., (Copyright (c) 2005 S. Karger AG, Basel.)